Telephone system.



F. M. SLOUGH.

TELEPHONE SYSTEM.

APPLICATION FILED OCT. 18. 1913.

1,169,291 Patented 172111.25, 1916.

2 SHEETS-SHEET I.

INVENTOR. WITNESSE V V a FRANK M.-SLOUGH 1 11%? Hi6 T 6% Patented Jan, 25,1916.

2 SHEETSSHEET 2.

INVENTOR. FRANK M .5.

VLOUGH HIS A rToRN HM. SLOUGH.

TELEPHONE SYSTEM. APPLICATION FILED ocT.1s. 191s.v

IWITZESSZVZS/ i alternating ringing current into the nnrrnn snares irarnnr FRANK M. SLOUGH, OF ELYRIA, OHIO, ASSIGNGR, TU THE GARFORD MANUFACTURING COMPANY, OF ELYIt-IA, OHIO, A CQR-PORATION OF OHIO.

TELEPHONE SYSTEM.

T0 allwhom it may concern:

Be it known that l, FRANK M. SLOUGH, a citizen of the United States, residing at Elyria, in the county of Lorain and State of Ohio, have invented certain new and useful Improvements in Telephone Systems; and I do hereby declare the'tollowing to be a full, clear, and exact description of the invention, such as will enable others skilled in the art towhich it appertains to make and use the same.

My invention relates to telephone systems and more particularly to systems which are adapted to ring the subscriber automatically after the connection has once been set up.

One of the objects of my invention is to provide means for removing the ringing current from the key shelf so as to prevent any possibility otinjury by the high voltage ringing current to the switchboard apparatus or the switchboard operators, and to sim plify the wiring of the system and providing what is spoken of in the art as a remote control for the ringing current.

' Another object of my invention is the provision 01 means for insuring the disconnection of ringing current from line when the subscriber responds, even though the influence caused by the response of the subscriber is very slight.

Another object of my invention is to provide in connection with the apparatus for accomplishing the other objects. means for preventing the application of ringing current to a line upon which a subscriber is already connected in circuit.

Another object of my invention is to accomplish the above-named objects without necessitating the carrying of high voltage manual ringing keys.

In previous attempts to provide systems which will cause automatic disconnection of the ringing current upon the response of the called subscriber, diiiiculty has been encountered, particularly when the subscribeus station is located on a party line. and when the party line is of the type generally known in the art as a harmonic party line. The duhculty referred to is due to the fact that in such a system as the latter, ringing currents of both low and high frequencies are used and quite often the high frequency ringing a i f higher voltage than the ringing current of low frequency. It has been Specification of Letters Patent.

, Application filed October 18, 1913. Seria1No.-?95,922.

found in practice that when many substations are placed on a line near to the telephone exchange, the ringing current sent out from the central exchange, which is ordinarily employed to do a great deal of the work of disconnecting itself automatically upon the response of the called subscriber, is, even prior to such a response, of greater volume than the total volume of current flowing" from the exchange upon the response of the subscriber on a line ina party line and ,of considerable length. I, therefore, provide means to diminish the efiect of the alternating ringing current to a degree proportional to its frequency. At the same time the eflect of the direct current is diminished but slightly.- 1 do this in such a way that the relay used for the purpose of initially causing the disconnection of the ringing current can also be used for the purpose of controlling the supervisory signals without affecting the talking qualities of the system.

Other objects of my invention and the invention itself will be better understood from a description of the particular embodiment illustrated in the accompanying drawings.

Figure 1 illustrates a telephone system in which my invention is embodied. Fig. 2 illustrates a second telephone system e1nploying a trunk circuit in which my inveir tion is employed.

Referring now to the drawing, and to the particular embodiments of the invention shown therein, at A l have shown e main station. sometimes known as the ce. al Sta-- tion. and at which the switchboard is located. A plurality of substations are shown, one at B upona telephone line 12, which leads fronrthe station E to the station A terminating preferably in a plurality of ticks, one of which is shown at J. Other substations are shown at C, D, Eand F, all which .may be upon the same telephone line 3- which leads to the main station A, termina"'ng thereat preferably in a ack J. At the main station I show apparatus'for connecting telephone lines together, which may consist of a cord circuit. in the form shown, the cord circuit terminates in plugs P and P, which together with the jacks J and J, illustrate a form of switching means for connecting the apparatus the main station to the subscribers lines. The cord circuit illustrated is what known as a .se con- 6,'7 and is illussignal is illustrated at 111 and the supervisory relays controlling said signal at 12 and 13.

At H is illustrated the battery employed at the main station. l i hile l have illustrated this battery at dilierent "LT-OSitiOl upon the diagram, it is understood tha may be the same battery, as l have in by employing the same reierence Cilul. for them all At M is illustrated a relay controilii V a relay.

actor the central station set; at la trolling the cord circuit; at 16, supervisory lamp; at l? and it the call supervisory relays; at 20, ill, 22 and :23, means for generating current to operate the signals 24: at the subscrihe stations. In the form shown, I have illustrated tour calling generators, though a .zuiunber may be employed. At 25, 26, 27 l. l h we illustrated interrupters for breaking the calling current into periods. fit 29, 30, 31 and 32 I illustrate means for controlling the connection of the calling curi n; the subscribers line, here shown as push i too ringing keys. rat-83, Eli, and illustrate additional means controlling application of this current to the called subscrihcrs line, which are here shown as relays. At U 1 illustrate the central station operators t The purpose of the appar is, its a 1. 1c lit a '1 the apparatus itserr run s cc o ter understood. from a (IiQbiil'lljJlOll of the operation oi the apparatus shown in the embodiment, which is as follows:-Assu:ning

that the subscriber at the substation B upon the line 12 desires to converse with one of the subscribers, such or example, as sub-- scriber F upon the line 3%, the receiver 40 is removed from the receiver hook 41,; which rises, closing a switch ll-l2, and placing the subscribers set including the transmitter 43 across the subscribers line in shunt of the hell 2% and condenser id. Currelzt then flows from ground at G, throu h the battery H, the relay 9, the switch l 5- 3 controlled by the cut-oil relay 11, side 2 line, through the bridge of the talzn 'the side 1 of line, through the switch 4 of the cut-off relay, through the windinc of the relay 9 to ground at G. Iiiagnct 9 ener ""ed, closing the switch 4:8 is) and. com ting the circuit through the lan i l-Il and the battery E. This lamp is placed in ich a position that its actuation noticed "by the operator, who inserts the plug 1? into contact 51, plug contact 52, third strand meager tl rough the coil 53 of the relay 14:, battery and ground G". The magnet 11 is energised, attracting the armatures 46 and? and cutting off the line relay and lamp from line. lhe Winding 53 of the relay 14 is energized, pulling up its armatures 54 and and connecting the operator"s set 0 line. A second circuit Was closed to from G ll, 50, 51, 52, 7, 56, magnet 13, battery l-l ground G energizing the magnet 13, winch attracts its armature 57, closingthe switch 57-58 in the circuit of the lamp ill", which would be lighted save for the fact iat the calling subscriber at l) 1S upon t; and that when the plug was incirci'iit was completed over both no through the calling subscribei"s the relay 12 in the cord circuit. (Ewing to the energiz...tion of the relay 12, the armature is'pulled up, opening the. circuit of the lamp 111 at 59G0. The operator then comn'iunicates with the calling )SLYl J learning what subscriber is desired, which it is here assumed is the subscriber l? upon the party line 3-l, though the subscriber desired may be upon an individual line. The operator first tests the called line to learn whether it is busy or not in the manner well known in the art, by touching the tip of the calling plug '20 to the sleeve 63 of the desired line, or in any other manner, may be preferred, Assuming that it is idle, she first inserts the plug P into the jack J, completing the connection between the cord and the called line. As soon ich is wound differentially to the 'ind- 3. .53, so that the relay 14 lets go of the armatures 5i and 55, cutting off the operators set from the connection and making it iniipossible for it to be reconnected to the cord circuit during the conversation period. A second circuit is completed when the plug inserted from G -G162-636l65- iit ffliily l8H and ground at G. When the relay 18 is energized tl'irough this cir- -uit, it attracts its armatures T0 and 71 closing a :uitch TO-72 for a purpose to be described and 7l73 in the circuit of the lamp 16, which is as follows: G-H-71 T3-i'i75 76-16 and G The lamp 16 operated overthis circuit and remains li 'hted until the called subscriber responds.

n it interrupted in a Way to be described. lhe apparatus is now in a posi-' tion tor the ringing operation, but before proceeding with that, I Wish to state that I have provided arrangements for removing armatures 87 and 88, closing at switch 87 89 and thereby locking itself up, the locking means here being shown as a locking circuit from ground at G -8789-338515- 7 87 67 5-7l-73-71-HG This looking circuit isunder the control both of the switching device PJ' and of the called subscriber, and will remain operative until either the subscriber responds or the plug is withdrawn, thus making it possible for the operator to interruptthe lock ng circuit should the called subscriber not respond. Also the relay 15 is energized when the foregoing circuit is completed, attracting its armatures 79 and 80, and interrupting the cord circuit at 79-81 and 8082, cutting oil the answering end of the cord circuit and the calling subscriber from the ringing operation, at the same time closing a switch 80-80 for the ringing circuit to be now described. When the armature 88 is attracted a switch 88-90 is closed and a circuit completed as follows: G 23--9128-92- 90S8939480-80 -6tip 971 tip spring 98-side 1 of line-the signal 2i at station F-side 3 of line 99-100-8-101- 102-battery H to ground at G. The commutator 28 is continuously rotated and the circuit or" the signaling currentis interrupted and made, allowing the ringing current to pass over the line and operate the signal Ql for definite periods of time and interrupting the signaling for definite periods of time. During the silent intervals, battery current is maintained connected to the line by the commutator 28. The current passing through the winding 102 of the relay 17 is not suitficient to operate such relay, owing to the resistance of the bell 24:. A part of this current passes through the branch 103-105-10l106-72-7O of this circuit, which includes a non-inductive resistance device 105, and the higher the frequency of current employed, the greaterwill be'the proportion current passing through the branch 105, since the branch 108 includes an inductive resistance. This ringing continues until the subscriber at F responds by removing the receiver 110 from the switch 111, completing a bridge 112 across the line 3-4, whereupon sufficient current flows to energize the winding 102 of the relay 17, which attracts the armatures 106 and 75. As soon as the armature 106 is attracted, all of the current will fiow through the winding 102, thus insuring a positive operation of that relay. lhe attraction of the armature opens the switch- I 75-76, removing the locking means from the relay 33, which lets go the armatures 87 and 88 cutting off the ringing generator and also interrupting the locking means. The circuit of the relay 15 is also broken when the switch 7576 is opened, releasing the armatures 79 and and closing the cord circuit. At the same time, the switch 80-83 will be, closed, closing a circuit as follows: G H-1021081O1.8 through the called line and the called subscribers set, back to the tip strand 680'831111 to G, over which the relay 17 is held up. The attraction of the armature 75 likewise interrupts the circuit of the lamp 16 at 7576. The apparatus is now in a posi tion for conversation with the operator lockedvout and the conversation continues to a. termination. Upon either party hanging up, the corresponding supervisory signal is operated, indicating to the operator that the conversation is terminated; for ample, assuming that the subscriber at B hangs up, the circuit of the relay 12 will be broken and the circuit of the lamp 111 completed at 5960. If it is the called subscriber F who hangs up, the circuit of the relay 17 will be interrupted, releasing the armature 75 and closing the circuit of the lamp 16 through 7576.. Observing that the subscribers have completed the conversation, the operator withdraws the plugs- P and P, interrupting the circuits of the relays 13 and 18, respectively, and restoring the system to normal. Supposing that the calledsubscriber did not respond, the operator withdraws the plug P", interrupting the circuit of the relay 18, which in releasing its armature 71, interrupted the locking circuit of the relay 33 at 71-73, restoring the system to normal.

lVl1ile I have illustrated the connecting apparatus as a cord circuit, the switching means for connecting it to a line circuit as a plug and jack, the locking means for the relay as a locking circuit, the means controlling the connection of the generating means to the cord circuit as including a relay, it will be understood that other suit able forms of this apparatus may be employed. l likewise may employ any suitable iorm of ringing key or arrangement for initially closing the circuit ofthe relay 33.

In Fig. 1 I have illustrated my invention employed in connection with a cord circuit, though it may readily be employed with other forms of circuits. In Fig. 2 I have illustrated it as applied to one character etc., to which my invention. may be applied,

which is as follows :At X is shown a telephone line which extends from a subscribeus station. at Y to a central station at 1V, here known as the main central station or A operatorsposition. At W is arranged a cord circuit adapted to connect a. calling line to the trunk circuit. At Z is shown the trunk station or what is known as the B operators position. At V I show a subscribers set upon a line U, here known as the called line. In the operation of the system, the A operator at the station W' is, in one way or another, informed of the trunk which she is intended. to use, which is here assumed to be the trunk illustrated in Fig. The plug P is inserted into the jack J of the trunk, completing a circuitas follows: 150--wnding' 151 of'relay 15215315%155--4.5t5-l57 through the high resistance relay 158-- 159-160*-161-l62 winding 163 of relay 152-battery 161. The relay 158 will be energized, but the resistance of this relay rill he such that the current will not be sutlicient to energize the relay 152. The lamp 165 will thus remain lighted. Wlen energized, the relay 158 will draw up its armature 166, closing the switch 167 and the circuit the signal 168 as foliows; 1G916S-1l36- 162' 1'z1 172 17a mumi at in. The

operation of this signal indicates to the 15' operator that the connection has'been nade, whereupon she inserts the plug P into the jack J completing a circuit through the called line cut-off relay 175 and the relay 176 as follows: 177175-178179-180- 17 6l7 8174. The relay 175 draws up its armatufits, cutting off the calling line appa-- ratus Q, from the line. The relay 176 attracts its armatures 1?:2 and 181, opening the switch 171172 and retiring the signal 168 The switch 17'2182 is closed for a purpose to be described. The switch 181-183 is closed for a purpose to be described. The operator now actuates one of the set of ring.- ing keys K, selecting theoneadapted to place upon the line ringing current of such a character as will operate the signal of the called subscriber. In this instance, we will assume that it is the key K which is operated, this key controlling the current from the generator 18 which it is assumed produces current suitable for the operation of the bell at the station. V. When the key K is depressed, a contact 186 engages a contact 187, closing a circuit as follows: 188-186- 187-189-190-191-2&5-2t419219 1821721:Z3 and 174. The relay 189 .1852 will be broken.

meager 219: the other branch 215non-inductive resistance 2% -221-'2'22223-188181- '22l225. The interrupter 185 is continuously operating, placing signaling current upon the line at predetermined intervals and maintaining battery connections to the line at alternate intervals. hen the called subscriber responds, a. low resistance shunt is placed upon the subscribers line around the signaling set, whereupon the strength of the line current is suliiciently great to operate the magnet 30, attracting its armatures 193 and The armature'193 upon being" attracted,- closes the circuit of the relay 2.11 as follows: 174r1'l'3-17:2182 19l19 2 l3252the winding 251 of the relay Ell-253, thus energizing the relay 2-11, which attracts its armatures 214 and 25-1 for a purpose to be described. During the ringing period the ringing lamp 240 was lighted through the contacts 172 and 182 of the relay 176. However, when the relay 241 was energized a circuit of the lamp 24:0 was broken. at 21-l*2l5, thus indicating to the operator that the called for subscriber has responded. When the armature 21-1 is attracted it makes a connection with the contact thus closing a locking circuit 1' i2-24 -.4.-255-25 125317-.P17317 18 3 and 19lfor the relay 24:1, thus causing it to remain energized until the connection s taken down, when the contacts 172 and At the time the relay 230 was energized upon the response of the called for subscriber, the armature 222 was attracted, thus breaking a circuit of the shunt 220 about the winding 217, so that the full strength of the battery and ringing current pases through the relay. This insures that the relay 24:1 shall be positively operated.

At the time the ringing lamp is extinguished, the locking circuit of the relay 189 is broken at 2% and M5, thus disconnecting the ringing generator from the line. lVhen the armature of the relay 2&1 is attracted. a circuit is completed. through the relay 231- as follows: 253--25-l-233256- the winding of the relay 2% to battery 257,

' thus energizing the relay 234, which attracts its armatures 235 and 236, closing the trunk conversational circuit. The system is now in condition for conversation, which may now take place. At the end of the conversation,.the receivers of the subscribers are returned to the hooks, interrupting the subscribers bridges. This act at the called sub- 210211212 to the junction 215 and inseam scribers station breaks the circuit of the relay 230, releasing the armatures 193 and and the shunt about the relay 158, which existed while the conversation was in progress. This shunt was of such low resistance as to permit the operation of the relay 152 and extinguishing of the lamp 165. Upon the interruption of this shunt when the called subscriber hangs up his receiver, the resistance of the relay 158 is again placed in circuit with the relay 152, whereupon the circuit of the lamp 165 is again closed, indicating to the A operator that the called subscriber has hung up his receiver, whereupon the plug P? is withdrawn from the jack J deenergizing the relay 158, completing a circuit through the lamp 168 as follows: 169- 168-166 250-25l-l92194,l82l72 173174. As soon as this lamp is operated, the B operator withdraws the plug P from the jack J restoring the system to normal.

I have illustrated my invention in connection with these two forms of circuits simply for the purpose of illustrating the same. I donot wish to be limited to the details of these circuits, but contemplate numerous and extensive departures from such details, being limited only by the scope of the claims.

I claim 1. In a telephone system, the combination of a main station, a telephone line leading to the main station, a plurality of substations on said line, telephone line connecting apparatus at the main station, switching means for connecting said apparatus to said telephone line, a calling signal device at each substation, a plurality of current producing means at the main station, each adapted to supply current to operate one of said calling signal devices, conductors forv connecting said current generating means to said switching apparatus, a plurality of manually operable switches, one for each of said cur rent generating means, conductors for said switches, said last named conductors being independent of the conductors for connecting the current generating means to the switching apparatus, mechanism controlled by said switches and means including a local circuit at the main station controlling the application of current generated by said current generating means to the telephone line controlled by said manually operable switches and said mechanism.

2. In a telephone system, the combination of a called telephone line, a plurality of substations on said line, a ringer at each substation, a main station to which said called line leac s, a cord circuit at the main station, a plug for the cord and a jack for the line by which the cord and line are connected together, a plurality of current generators at the main station, each adapted to supply current to operate one of the ringers at one of the substations, a plurality of conductors for connecting said generators to the plug of the cord, a plurality of manually controlled switches, one for each current generator, conductors for said switches independent of the conductors connecting the current generating means to the plug, a plurality of relays, one for each switch, each relay being controlled by a corresponding one of said switches and means including a local circuit controlling the application of current generated by said generators to the telephone line controlled by said manually operated switches and said relays.

3. In a telephone system, the combination of a main station, a called telephone line leading to the main station, a plurality of substations on the line, a, ringer at each substation, a cord circuit at the main station, a plug for the cord and a jack for the line through which the line and cord are connected, a plurality of current generators at the main station, conductors for connecting each generator to the plug, a plurality of relays, one controlling the connection of each of said generators to the plug, a circuit local to the main station, including a plurality of branches, one of said relays being in each of said branches, a plurality of manual switches, one in each branch removed from the conductors connecting the generators to the plug and means for locking up eachyof said relays when its corresponding switch is operated.

' 4. In a telephone system, the combination of a main station and a plurality of substations, telephone lines connecting said substations to said main station, apparatus at the main station for connecting two of said telephone lines together, switching means for connecting said apparatus to a called telephone line, calling signal devices at the substations,current generators at the main station for supplying current to operate said calling devices, a plurality of ringing switches and a plurality of relays each controlled by a companion ringing switch, a circuit including a plurality of branches, each branch including a relay and a companion ringing switch, means including a portion of said circuit for locking up each relay when its companion ringing switch has been operated, and conductors for connecting the generators to the switching means, said conductors being independent of said circuit branches including said relays and ringing switches.

5. In a telephone system, the combination of a main'station, a cord circuit at the main station, a called line leadingto the main station, a plurality of substations on said line, a ringer at each substation, a plug for the cord and a jack for the line, by which they are connected together, a plurality of current generating means at the main station, associated with the cord circuit thereat and adapted to supply current to operate the ringers, a ringingcireuit including a plurality of ringing leads, one of said generating means being in each of said leads, a ringing relay controlling the ringing circuit, a plurality of branches ofsaid circuit, a re lay in each of said branches controlling one of said ringing leads, and amanual switch in-each of said branches controlling said ringing relay circuit through its branch and the relay therein, and means for locking the circuit of the ringing relay after any of said switches have been operated.

6. In a telephone system, the combination of a main station,- a cord circuit at the main station, a called telephone line leading to the main station, a plurality of substations on the line, a ringer at each substation, switching apparatus for connecting the cord and line together, a plurality of current generating means associated with the cord at the main station and adapted to supply current to operate the ringers at the substations, a ringing circuit, a lead from each of said generating means in said circuit, a ringing relay controlling the ringing circuit, a ringing relay circuit, a plurality of branches of said ringing relay circuit, an electromagnetic relay in each of said branches, each of said last named relays con trolling one of said ringing leads, a manually operated switch in each of said branches controlling said. ringing relay circuit and an arm of each branch containing normally open contacts controlled by the relay in said branch through Which said relay locks the ringing relay circuit when said relay is operated.

7. In a telephone system, the combination of a main station and a called telephone line, link conductors at the main station lcr connecting telephone lines together, substations on said line, a calling signal at each substation, a plurality of current generating means adapted to produce current to operate the calling signals, a ringing circuit, a ringii'ig lead connectin each of said current generating means in .id ringing circuit, a ringing relay, a circuit for the ringing relay, a plurality of branches oil said ringing relay circuit, a relay in each of said branches, each of said relays controlling one of said ringing leads and manually controlled contacts in each oi said branches controlling said ringing relay circuit.

8. In a telephone system, the combination of a main station and a called telephone line, link conductors at the main station for connecting telephone lines together, substations on said line, a calling signal at each substatie a plurality of current generating means adapted to produce current to operatethe calling signals, a ringing circuit, a ringing lead connecting each of said current generating means in said ringing circuit, a ringing re a y, a circuit for the ringing relay, a plurality of branches of said ringing relay circuit, a relay in each of said branches, each of said relays controlling one of said ring ing leads, manually controlled contacts in each of said branches controlling said ringing relay circuit and means to maintain said circuit closed after said manually controlled contacts have been operated and released.

9. In a telephone system, the combination of a main station and a called telephone line, link conductors at the main station for connecting telephone lines together, substations on said line, a calling signal at each substation, a plurality of current generating means adapted to produce current to operate the calling signals, a ringing circuit, a ringing lead connecting each of said current generating means in said ringing circuit, a ringing i'cla a circuit for the ringing relay, a plurality of branches of .said ringing relay circuit, a relay in each of said branches, each of said relays controlling one of said ringing leads", manually controlled contacts in each of said branches controlling said ring ing relay circuit, and means controlled by said branch relays for maintaining said ringing relay circuit after said manually controlled contacts hayebeen operated and released 10. In a telephone system, the combina-' tion of a main station, telephone line interconnecting mechanism at the main station, a telephone line leading to the main station, switching apparatus for connecting said mechanism to said telephone line, a pin rality of signaling devices on the telephone line, a plurality of current generating means, a ringing circuit, ringing leads in- I eluding said means in said ringing circuit,

each lead containing normally open contacts,

a ringing relay, a ringing relay circuit including said ringing relay, a plurality of' branches of said ringing relay circuit, a magnet in each branch, each magnet controlling the normally open contacts in one of said ringing leads, normally open manually controlled contacts in each of said branches and means for automatically maintaining a branch and said ringing relay-circuit after the manually controlled contacts in said branch have been closed and opened.

11. In a telephone system, the combination of a selective signaling circuit, a plurality of electro-rasponsiye devieesin, said circuit, plurality of sources of current adapted to be connected in said circuit to supply current to operate said devices, a ringing'relay controlling the connection of a source to said deyices, a plurality of selective relays, each adapted to include a particular one of said sources of ringing current with the contacts of said ringing relay, a circuit for the magnet of said ringing ielay, a plurality of manually operated switches, each of said switches being adapted to include a particular selective relay in the circuit of the magnet of said ringing relay, and automatic means to maintain the ringing relay magnet circuit after the restoration of said switch to normal.

12, In a telephone system, the combination of a telephone line, a plurality of substations on said line, each including an elec tro-responsive device and a manually operable switch, a plurality or sources of current adapted to be connected to said telephone lines to supply current to selectively operate said clectro-responsire devices, a ringing relay controlling the connection of said sources of current to sa telephone line, a plurality of selective relays, each adapted to include a particular one of said sources of ringing current with the contacts of said ringing relay, a circuit for the magnet oi said ringing relay, a plurality of .ianually operable switches. each of said switches being adapted to include a particular selective relay in the circuit of the magnet oi'. said ringing relay, automatic means to maintain said ringing relay magnet circuit after the restoration of said last named manually operable switch to normal and means controlled by the manually operable switches at the substations for restoring the ringing relay and the selective relays to normal. I

1?). In a telephone system, the combine tion of a telephone line, a plurality of substations on said line, each line including a ringer and a hoolcswitch, a. plurality of sources of current, each adapted to be connected to said telephone line to supply current to selectively operateLsaid ringers, a ringing relay controlling the connection of a source of current to said line, a plurality of selective relays. each controlling the con nection of a particular one of said sources of ringing current with the contacts of said ringing relay and to said telephone line, a circuit for themagnet of said ringing relay, aplurality of manually operated switches, each of which controls the connection of a particular selective relay in the circuit of the magnet or". said ringing relay, automatic means to maintain said ringing relay magnet circuit after the restoration of said switch to normal and means controlled by the hook-switches at the substations for restoring the ringing relay to normal 14:. In a telephone system, thecombination of a telephone line, a plurality of substations on said line, each line including a r and a hook-switch, a plurality of sources of current, each adapted to be connected to said telephone line to supply cur rent to selectively operate said ringers, a ringing relay controlling the connection of a source of current to said line, a plurality of selective relays, each controlling the connection of a particular one of said sources of ringing current with the contacts of said ringing relay and to said telephone line, a circuit for the magnet of saidv ringing relay, a plurality of manually operated switches, each of which controls the connection of a particular selective relay in'the circuit of the magnet of said ringing relay, automatic means to maintain said ringing relay magnet circuit after the restoration of said switch to normal and means controlled by the hook-switches at the substations for restoring the selective relays to normal.

15. In a telephone system, the combination of a telephone line, a plurality of substations on said line, connecting apparatus for connecting said telephone line With other telephone lines, signaling means at each subscribers station, means for generating current to operate said signaling means, a subscribers telephone at each station, a source of current at the main station for energizing said telephone for talking purposes, a relay at the main station in the circuit of said talking current source, a circuit for connecting said generating means to said subscribers signaling means, said last named circuit including said relay and a shunt about said relay and contacts on said relay, said contacts being adapted to removesaid shunt when the relay is connected in the talking circuit of said subscriberstelephone.

16.-In a telephone system, the combination of a main station and a plurality of substations, telephone lines for connecting said substations to. said main station, apparatus at the main station for connecting telephone lines together, signaling means at the subscribers station, means for generating current to operate said signaling means, a relay at the main station controlled by the called subscriber, a circuit for connectingsaid generating means to the signaling means at the subscribers station, said circuit including said relay and a shunt about said relay controlled by said relay.

1?. In a telephone system, the combination of a plurality of telephone lines, substations on' said lines, apparatus for connecting telephone lines together, signaling means at the subscribers station, means for generating current to operate said signaling means, a subscriber controlled device associated with the connecting apparatus, a cir-' cuit for connecting said generating means to said subscribefis signaling means, including said subscriber controlled device and a shunt about said subscriber controlled device controlled by said subscriber controlled device. I

18. In a telephone system, the combination of a mainstation and a plurality of substations, telephone lines for connecting said substations to said main station, ap-

. paratus at the mainstation for connecting telephone lines together, signaling means at the subscrlbers station, means for generaterating means to saicl. subscribers signaling means lnclucling said subscrlber cont-rolled devlce and a, shunt about said subscrlbei' controlled device controlled by said sub- 10 sei'iber controlled device.

In Witness whereof I have afiixecl my signature in the presence of two Witnessesthis 15th day of ()ciober 1913.

FRANK M. SLOUGH. lVitnesses G120. E. ROBERTS;

R. G. Ssxns. 

